A significant disadvantage of digital hearing aid devices is the relatively short battery life. Typically, the battery life of a digital hearing aid is a week or ten days. Therefore, devices may use various methods to conserve battery life. One method conserves battery life by detecting when the wearer sleeps at night. The device reduces the amount of energy consumed by the processor in such circumstances. However, this method does not take into consideration situations where the wearer is awake but there is no discernable sound to be processed by the device. The above method is not designed to cease processor and clock functions at any time, day or night, when the decibel level is low enough that the wearer doesn't need to be aware that a particular sound has occurred.
However, a digital hearing aid device must awaken quickly enough when a noteworthy sound occurs. Ideally the performance of the device from the point of view of the wearer should not be degraded. Examples of this kind of device behavior can be found in cardiac pacemakers. Pacemaker designers emphasize the need for the processor to go to sleep in order to conserve battery life, since surgery may be necessary if the battery has to be replaced in a pacemaker. This extreme requirement is not needed in a hearing aid device, since the battery is easily replaced. However, the remarkably short life of batteries in existing hearing aid devices results in consumer frustration, as well as unnecessary expense and inconvenience.